Trump took fire from Senate Armed Services Committee Chairman John McCain (R-Ariz.) Sunday for saying that Russia would take care of ISIS, but he doubled down in an interview with George Stephanopoulos on ABC’s "This Week."

“They don’t want ISIS going into Russia either. So they’re not bombing them yet,” he said.

U.S. officials say Russian airstrikes have targeted U.S.-backed rebels, but Trump said it's only a matter of time before Russia's military begins to focus on ISIS for fear it could sponsor terrorism in Moscow.

Trump said the United States should stay out of Syria and let the violent conflict shake out on its own.

“This does not sound like me very much, but I want to sit back and I want to see what happens,” he said.

Trump rebuffed calls by Democratic front-runner Hillary Clinton and Ohio Gov. John Kasich, a GOP presidential candidate, for the United States to establish a no-fly zone over Syria to respond to Russian airstrikes against U.S.-backed rebels.

He also predicted Syria would become a quagmire for Russian President Vladimir Putin.

“It’s not going to be great for them if you want to know the truth,” he said, citing the costly intervention in Afghanistan that contributed to the breakup of the Soviet Union.

“I mean they essentially went bankrupt. It destroyed the Soviet Union,” he said of the Afghanistan war. “Now they’re going into Syria, there are so many traps, there are so many problems.

“When I heard they were going in to fight ISIS, I said, ‘Great, let them,’ ” he said.

Trump said President Obama’s decision to back rebels in Syria is risky.

“I spoke to a general who you know very much, he said, 'Mr. Trump, we have no idea who these people are.' They may be worse than Assad,” he said.